Question

The erythrocyte membrane consists of different phospholipids that are asymmetrically distributed across the membrane. Explain the different lipid composition of the inner and outer leaflets of the erythrocyte membrane. Which leaflet would you expect to be the most permeable to Na+ or Cl- ions? Explain your answer.

Answer 1

The plasma membrane is made up of two leaflets, inner leaflet and outer leaflet. The composition of phospholipids in both the leaflet is different -

A. Outer leaflet - phosphatidylcholine, sphingomyelin, and glycolipids

B. Inner leaflet - phosphatidylethanolamine, phosphatidylserine, phosphatidylinositol

More permeable leaflet will be the outer leaflet because it will be less specific to the movement of molecules across the surface of red blood cells in comparison to the inner leaflet which will be more specific. Also, it is possible that the outer leaflet is having more number of transport proteins which will increase the permeability of outer leaflet for the transportation of ions.

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